Active Matrix Organic Light Emitting Diode (AMOLED) displays have been developed for use in a variety of computing displays and devices, including notebook computers, desktop computers, tablet computing devices, mobile phones (e.g., smart phones) automobile in-cabin displays, on appliances, as televisions, etc. An AMOLED display generally includes an array of pixels, with each pixel defining an active pixel area and an associated pixel circuit for driving an active pixel area.
A conventional display pixel used in AMOLEDs generally has two thin film transistors (“TFTs”), a storage capacitor, and an organic light emitting diode (“OLED”). The two TFTs include a switching TFT and a driver TFT. During operation, the switching TFT is turned on, resulting in the data signal being propagated to a storage node. This action charges the storage capacitor and sets up the gate voltage of the driver TFT. The driver TFT then converts the data signal into the electrical current. Thus, the output current of the driver TFT determines the resulting brightness of the OLED. The conventional pixel uses a storage capacitor to hold the electrical charges in the pixel. However, the charges stored in the capacitor constantly leak out, and therefore, refresh cycles are required to maintain a static image. Such refresh cycles increase the power consumption of the display system.
Further, since an OLED is a current-driven device whose luminance is determined by the passing current, uniformity between current provided to different pixels of an OLED panel is crucial for providing quality images to a panel implementing current-mode AMOLEDs.